This invention relates to managing (i.e., charging and discharging pressurized fluid) from a fluid receiving structure. More specifically, this invention relates to an accumulator which receives fluid pressure and is configured to store and subsequently discharge the fluid pressure.
Fluid circuits which include an energy storage capability for the purpose of capturing fluid energy produced by the circuit and thereafter discharging are well known. It is common to employ a containment vessel, such as an accumulator to store a significant volume of fluid. In addition to fluid storage these containment vessels include an internal mechanism which pressurizes the fluid being received therein such that the fluid may be later discharged at a significantly elevated pressure.
One type of well-known accumulator is the gas filled accumulator which includes an internal mechanism consisting of a gas filled bladder. As fluid pressure from a fluid circuit is introduced into the accumulator to xe2x80x9cchargexe2x80x9d the accumulator, the bladder and the gas within is compressed resulting in the fluid contained within the accumulator being pressurized. U.S. Pat. No. 2,283,439 issued to Herman, illustrates such an accumulator and gas filled bladder or diaphragm.
One problem with the gas filled accumulator is that the diaphragm is prone to rupture and periodic maintenance and consequently, increased cost of maintenance. Additionally, a significant cost is attributable to ensuring that the bladder and the pressure vessel of the accumulator are designed pursuant to compressible gas pressure vessel regulations. Moreover, the bladder is often constructed of an elastomeric material which exhibits performance degradation, and possibly performance failure, with elevated operating temperatures.
Another type of accumulator is the piston type accumulator having a pressure vessel cylinder, a reciprocable plunger therein and a spring to resist plunger movement which provides a charge to the fluid introduced into the cylinder. One advantage of the piston type accumulator is that compressible fluid is not required within the vessel since the pressurizing mechanism is provided by a spring force imparted on the plunger. U.S. Pat. No. 5,845,749 issued to Moretz et al. is one example of a piston type accumulator.
One problem with the piston type accumulator is that either a series of springs or one large spring is required if high-pressure usage is warranted. It is known to employ a nested arrangement of Bellville springs to provide a large spring force. Yet, even with multiple Bellville springs the range of deflection, and associated storage volume capability is limited. Moreover, since Bellville springs develop a high force over a small deflection the stress within the spring materials becomes significant and, as a result, premature failure and/or periodic maintenance of these springs is common. Also, the outer extents of the springs develop high contact forces as each spring is collapsed and consequently, the contacting surfaces (i.e., the surface between springs and/or the spring/plunger interface) experience premature wear and failure.
Therefore, an accumulator having high-pressure capabilities, and additionally, a significant volume capacity which, in turn, would charge and discharge substantially all of the fluid contained therein at a substantially constant pressure would be desirable.
The present invention provides an accumulator assembly for storing pressurized fluid including a housing and a partition provided in the housing being moveable in response to fluid pressure imparted on the partition. A deflection member is disposed in the housing and is displaceable between a first position and a second position. The deflection member includes at least one deflection element including a first end and a second end and a flexing portion therebetween. The deflection member provides a resistive force between the first and the second positions of the deflection member in response to movement of the partition. The resistive force is substantially constant between the first and said second positions of the deflection member.
The present invention further provides a method for managing pressurized fluid using an accumulator assembly and the accumulator assembly includes a housing, a partition provided in the housing and moveable in response to fluid pressure being imparted on the partition, and a deflection member disposed in the housing. The method includes receiving fluid pressure within said housing; displacing the deflection member from a first position to a second position in response to the fluid pressure being received in the housing; and causing a substantially constant force on the partition through the deflection member between the first and second positions of the deflection member.